Effect of Partially Purified Fraction from the Crude Aqueous Extract of Allium sativum L. on Sperm Immobilization

To elucidate the nature and the probable mode of action of the partially purified in vitro human sperm immobilizing fraction of Allium sativum L., with a view to develop a herbal intravaginal spermicidal agent partial purification was carried out using different types of chromatography. After each step of purification, the purified fractions were tested on human ejaculated sperm to verify the instant immobilization activity and thus the most active fraction underwent further purification. For characterization of its nature, Nuclear magnetic spin resonance (NMR), Gas Liquid Chromatography (GLC) and Electron spray ionization mass spectroscopy (ESI-MS) were carried out. In order to understand the mechanism of action, several sperm functional parameters such as viability, Hypo-Osmotic Swelling (HOS), 5´ nucleotidase, acrosin and acrosome intactness were estimated when the sperm cells were incubated with the partially purified extract. Characterization showed that the partially purified fraction contained β-linked heptasaccharide consisting of glucose molecule as aglycone part, whose approximate molecular weight was 1152. The minimum inhibitory concentration (MIC) and Effective Concentration 50 (EC50) of this fraction was 50 mg/ml and 16 mg/ml, respectively. When treated sperm was compared with the control, there was a loss of more than 65% in the activity of plasma membrane marker enzyme 5’ nucleotidase, 55% loss in sperm viability, 78% reduction in HOS 80% decrease in the activity of acrosin and acrosome intactness. Results revealed the in vitro sperm immobilization activity of the partially purified extract, consisting of glucose molecules as one of the major constituents, which exert its effect mainly on plasma and acrosomal membrane architecture.